package binance

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/gorilla/websocket"
	"github.com/thrasher-corp/gocryptotrader/currency"
	"github.com/thrasher-corp/gocryptotrader/exchanges/asset"
	"github.com/thrasher-corp/gocryptotrader/exchanges/order"
	"github.com/thrasher-corp/gocryptotrader/exchanges/orderbook"
	"github.com/thrasher-corp/gocryptotrader/exchanges/ticker"
	"github.com/thrasher-corp/gocryptotrader/exchanges/websocket/wshandler"
	"github.com/thrasher-corp/gocryptotrader/exchanges/websocket/wsorderbook"
	"github.com/thrasher-corp/gocryptotrader/log"
)

const (
	binanceDefaultWebsocketURL = "wss://stream.binance.com:9443"
	pingDelay                  = time.Minute * 9
)

var listenKey string

// WsConnect intiates a websocket connection
func (b *Binance) WsConnect() error {
	if !b.Websocket.IsEnabled() || !b.IsEnabled() {
		return errors.New(wshandler.WebsocketNotEnabled)
	}

	var dialer websocket.Dialer
	var err error
	if b.Websocket.CanUseAuthenticatedEndpoints() {
		listenKey, err = b.GetWsAuthStreamKey()
		if err != nil {
			b.Websocket.SetCanUseAuthenticatedEndpoints(false)
			log.Errorf(log.ExchangeSys, "%v unable to connect to authenticated Websocket. Error: %s", b.Name, err)
		}
	}

	pairs := b.GetEnabledPairs(asset.Spot).Strings()
	tick := strings.ToLower(
		strings.Replace(
			strings.Join(pairs, "@ticker/"), "-", "", -1)) + "@ticker"
	trade := strings.ToLower(
		strings.Replace(
			strings.Join(pairs, "@trade/"), "-", "", -1)) + "@trade"
	kline := strings.ToLower(
		strings.Replace(
			strings.Join(pairs, "@kline_1m/"), "-", "", -1)) + "@kline_1m"
	depth := strings.ToLower(
		strings.Replace(
			strings.Join(pairs, "@depth/"), "-", "", -1)) + "@depth"

	wsurl := b.Websocket.GetWebsocketURL() +
		"/stream?streams=" +
		tick +
		"/" +
		trade +
		"/" +
		kline +
		"/" +
		depth
	if listenKey != "" {
		wsurl += "/" +
			listenKey
	}

	b.WebsocketConn.URL = wsurl
	b.WebsocketConn.Verbose = b.Verbose

	err = b.WebsocketConn.Dial(&dialer, http.Header{})
	if err != nil {
		return fmt.Errorf("%v - Unable to connect to Websocket. Error: %s",
			b.Name,
			err)
	}
	b.WebsocketConn.SetupPingHandler(wshandler.WebsocketPingHandler{
		UseGorillaHandler: true,
		MessageType:       websocket.PongMessage,
		Delay:             pingDelay,
	})

	enabledPairs := b.GetEnabledPairs(asset.Spot)
	for i := range enabledPairs {
		err = b.SeedLocalCache(enabledPairs[i])
		if err != nil {
			return err
		}
	}

	go b.wsReadData()
	go b.KeepAuthKeyAlive()
	return nil
}

// KeepAuthKeyAlive will continuously send messages to
// keep the WS auth key active
func (b *Binance) KeepAuthKeyAlive() {
	b.Websocket.Wg.Add(1)
	defer func() {
		b.Websocket.Wg.Done()
	}()
	ticks := time.NewTicker(time.Minute * 30)
	for {
		select {
		case <-b.Websocket.ShutdownC:
			ticks.Stop()
			return
		case <-ticks.C:
			err := b.MaintainWsAuthStreamKey()
			if err != nil {
				b.Websocket.DataHandler <- err
				log.Warnf(log.ExchangeSys, b.Name+" - Unable to renew auth websocket token, may experience shutdown")
			}
		}
	}
}

// wsReadData receives and passes on websocket messages for processing
func (b *Binance) wsReadData() {
	b.Websocket.Wg.Add(1)
	defer func() {
		b.Websocket.Wg.Done()
	}()
	for {
		select {
		case <-b.Websocket.ShutdownC:
			return

		default:
			resp, err := b.WebsocketConn.ReadMessage()
			if err != nil {
				b.Websocket.ReadMessageErrors <- err
				return
			}
			b.Websocket.TrafficAlert <- struct{}{}
			err = b.wsHandleData(resp.Raw)
			if err != nil {
				b.Websocket.DataHandler <- err
			}
		}
	}
}

func (b *Binance) wsHandleData(respRaw []byte) error {
	var multiStreamData map[string]interface{}
	err := json.Unmarshal(respRaw, &multiStreamData)
	if err != nil {
		return err
	}
	if method, ok := multiStreamData["method"].(string); ok {
		// TODO handle subscription handling
		if strings.EqualFold(method, "subscribe") {
			return nil
		}
		if strings.EqualFold(method, "unsubscribe") {
			return nil
		}
	}
	if e, ok := multiStreamData["e"].(string); ok {
		switch e {
		case "outboundAccountInfo":
			var data wsAccountInfo
			err := json.Unmarshal(respRaw, &data)
			if err != nil {
				return fmt.Errorf("%v - Could not convert to outboundAccountInfo structure %s",
					b.Name,
					err)
			}
			b.Websocket.DataHandler <- data
		case "outboundAccountPosition":
			var data wsAccountPosition
			err := json.Unmarshal(respRaw, &data)
			if err != nil {
				return fmt.Errorf("%v - Could not convert to outboundAccountPosition structure %s",
					b.Name,
					err)
			}
			b.Websocket.DataHandler <- data
		case "balanceUpdate":
			var data wsBalanceUpdate
			err := json.Unmarshal(respRaw, &data)
			if err != nil {
				return fmt.Errorf("%v - Could not convert to balanceUpdate structure %s",
					b.Name,
					err)
			}
			b.Websocket.DataHandler <- data
		case "executionReport":
			var data wsOrderUpdate
			err := json.Unmarshal(respRaw, &data)
			if err != nil {
				return fmt.Errorf("%v - Could not convert to executionReport structure %s",
					b.Name,
					err)
			}
			var orderID = strconv.FormatInt(data.OrderID, 10)
			oType, err := order.StringToOrderType(data.OrderType)
			if err != nil {
				b.Websocket.DataHandler <- order.ClassificationError{
					Exchange: b.Name,
					OrderID:  orderID,
					Err:      err,
				}
			}
			var oSide order.Side
			oSide, err = order.StringToOrderSide(data.Side)
			if err != nil {
				b.Websocket.DataHandler <- order.ClassificationError{
					Exchange: b.Name,
					OrderID:  orderID,
					Err:      err,
				}
			}
			var oStatus order.Status
			oStatus, err = stringToOrderStatus(data.CurrentExecutionType)
			if err != nil {
				b.Websocket.DataHandler <- order.ClassificationError{
					Exchange: b.Name,
					OrderID:  orderID,
					Err:      err,
				}
			}
			var p currency.Pair
			var a asset.Item
			p, a, err = b.GetRequestFormattedPairAndAssetType(data.Symbol)
			if err != nil {
				return err
			}
			b.Websocket.DataHandler <- &order.Detail{
				Price:           data.Price,
				Amount:          data.Quantity,
				ExecutedAmount:  data.CumulativeFilledQuantity,
				RemainingAmount: data.Quantity - data.CumulativeFilledQuantity,
				Exchange:        b.Name,
				ID:              orderID,
				Type:            oType,
				Side:            oSide,
				Status:          oStatus,
				AssetType:       a,
				Date:            time.Unix(0, data.OrderCreationTime*int64(time.Millisecond)),
				Pair:            p,
			}
		case "listStatus":
			var data wsListStauts
			err := json.Unmarshal(respRaw, &data)
			if err != nil {
				return fmt.Errorf("%v - Could not convert to listStatus structure %s",
					b.Name,
					err)
			}
			b.Websocket.DataHandler <- data
		default:
			b.Websocket.DataHandler <- wshandler.UnhandledMessageWarning{Message: b.Name + wshandler.UnhandledMessage + string(respRaw)}
			return nil
		}
	}
	if stream, ok := multiStreamData["stream"].(string); ok {
		streamType := strings.Split(stream, "@")
		if len(streamType) > 1 {
			if data, ok := multiStreamData["data"]; ok {
				rawData, err := json.Marshal(data)
				if err != nil {
					return err
				}
				switch streamType[1] {
				case "trade":
					var trade TradeStream
					err := json.Unmarshal(rawData, &trade)
					if err != nil {
						return fmt.Errorf("%v - Could not unmarshal trade data: %s",
							b.Name,
							err)
					}

					price, err := strconv.ParseFloat(trade.Price, 64)
					if err != nil {
						return fmt.Errorf("%v - price conversion error: %s",
							b.Name,
							err)
					}

					amount, err := strconv.ParseFloat(trade.Quantity, 64)
					if err != nil {
						return fmt.Errorf("%v - amount conversion error: %s",
							b.Name,
							err)
					}

					b.Websocket.DataHandler <- wshandler.TradeData{
						CurrencyPair: currency.NewPairFromFormattedPairs(trade.Symbol, b.GetEnabledPairs(asset.Spot),
							b.GetPairFormat(asset.Spot, true)),
						Timestamp: time.Unix(0, trade.TimeStamp*int64(time.Millisecond)),
						Price:     price,
						Amount:    amount,
						Exchange:  b.Name,
						AssetType: asset.Spot,
					}
				case "ticker":
					var t TickerStream
					err := json.Unmarshal(rawData, &t)
					if err != nil {
						return fmt.Errorf("%v - Could not convert to a TickerStream structure %s",
							b.Name,
							err.Error())
					}

					b.Websocket.DataHandler <- &ticker.Price{
						ExchangeName: b.Name,
						Open:         t.OpenPrice,
						Close:        t.ClosePrice,
						Volume:       t.TotalTradedVolume,
						QuoteVolume:  t.TotalTradedQuoteVolume,
						High:         t.HighPrice,
						Low:          t.LowPrice,
						Bid:          t.BestBidPrice,
						Ask:          t.BestAskPrice,
						Last:         t.LastPrice,
						LastUpdated:  time.Unix(0, t.EventTime*int64(time.Millisecond)),
						AssetType:    asset.Spot,
						Pair: currency.NewPairFromFormattedPairs(t.Symbol, b.GetEnabledPairs(asset.Spot),
							b.GetPairFormat(asset.Spot, true)),
					}
				case "kline_1m", "kline_3m", "kline_5m", "kline_15m", "kline_30m", "kline_1h", "kline_2h", "kline_4h",
					"kline_6h", "kline_8h", "kline_12h", "kline_1d", "kline_3d", "kline_1w", "kline_1M":
					var kline KlineStream
					err := json.Unmarshal(rawData, &kline)
					if err != nil {
						return fmt.Errorf("%v - Could not convert to a KlineStream structure %s",
							b.Name,
							err)
					}

					b.Websocket.DataHandler <- wshandler.KlineData{
						Timestamp: time.Unix(0, kline.EventTime*int64(time.Millisecond)),
						Pair: currency.NewPairFromFormattedPairs(kline.Symbol, b.GetEnabledPairs(asset.Spot),
							b.GetPairFormat(asset.Spot, true)),
						AssetType:  asset.Spot,
						Exchange:   b.Name,
						StartTime:  time.Unix(0, kline.Kline.StartTime*int64(time.Millisecond)),
						CloseTime:  time.Unix(0, kline.Kline.CloseTime*int64(time.Millisecond)),
						Interval:   kline.Kline.Interval,
						OpenPrice:  kline.Kline.OpenPrice,
						ClosePrice: kline.Kline.ClosePrice,
						HighPrice:  kline.Kline.HighPrice,
						LowPrice:   kline.Kline.LowPrice,
						Volume:     kline.Kline.Volume,
					}
				case "depth":
					var depth WebsocketDepthStream
					err := json.Unmarshal(rawData, &depth)
					if err != nil {
						return fmt.Errorf("%v - Could not convert to depthStream structure %s",
							b.Name,
							err)
					}

					err = b.UpdateLocalCache(&depth)
					if err != nil {
						return fmt.Errorf("%v - UpdateLocalCache error: %s",
							b.Name,
							err)
					}

					currencyPair := currency.NewPairFromFormattedPairs(depth.Pair, b.GetEnabledPairs(asset.Spot),
						b.GetPairFormat(asset.Spot, true))
					b.Websocket.DataHandler <- wshandler.WebsocketOrderbookUpdate{
						Pair:     currencyPair,
						Asset:    asset.Spot,
						Exchange: b.Name,
					}
				default:
					b.Websocket.DataHandler <- wshandler.UnhandledMessageWarning{Message: b.Name + wshandler.UnhandledMessage + string(respRaw)}
				}
			}
		}
	}
	return nil
}

func stringToOrderStatus(status string) (order.Status, error) {
	switch status {
	case "NEW":
		return order.New, nil
	case "CANCELLED":
		return order.Cancelled, nil
	case "REJECTED":
		return order.Rejected, nil
	case "TRADE":
		return order.PartiallyFilled, nil
	case "EXPIRED":
		return order.Expired, nil
	default:
		return order.UnknownStatus, errors.New(status + " not recognised as order status")
	}
}

// SeedLocalCache seeds depth data
func (b *Binance) SeedLocalCache(p currency.Pair) error {
	ob, err := b.GetOrderBook(
		OrderBookDataRequestParams{
			Symbol: b.FormatExchangeCurrency(p, asset.Spot).String(),
			Limit:  1000,
		})
	if err != nil {
		return err
	}

	return b.SeedLocalCacheWithBook(p, &ob)
}

func (b *Binance) SeedLocalCacheWithBook(p currency.Pair, orderbookNew *OrderBook) error {
	var newOrderBook orderbook.Base
	for i := range orderbookNew.Bids {
		newOrderBook.Bids = append(newOrderBook.Bids, orderbook.Item{
			Amount: orderbookNew.Bids[i].Quantity,
			Price:  orderbookNew.Bids[i].Price,
		})
	}
	for i := range orderbookNew.Asks {
		newOrderBook.Asks = append(newOrderBook.Asks, orderbook.Item{
			Amount: orderbookNew.Asks[i].Quantity,
			Price:  orderbookNew.Asks[i].Price,
		})
	}

	newOrderBook.Pair = p
	newOrderBook.AssetType = asset.Spot
	newOrderBook.ExchangeName = b.Name
	newOrderBook.LastUpdateID = orderbookNew.LastUpdateID

	return b.Websocket.Orderbook.LoadSnapshot(&newOrderBook)
}

// UpdateLocalCache updates and returns the most recent iteration of the orderbook
func (b *Binance) UpdateLocalCache(wsdp *WebsocketDepthStream) error {
	currencyPair := currency.NewPairFromFormattedPairs(wsdp.Pair, b.GetEnabledPairs(asset.Spot),
		b.GetPairFormat(asset.Spot, true))
	currentBook := b.Websocket.Orderbook.GetOrderbook(currencyPair, asset.Spot)

	// Drop any event where u is <= lastUpdateId in the snapshot.
	// The first processed event should have U <= lastUpdateId+1 AND u >= lastUpdateId+1.
	// While listening to the stream, each new event's U should be equal to the previous event's u+1.
	if wsdp.LastUpdateID <= currentBook.LastUpdateID {
		return nil
	}

	var updateBid, updateAsk []orderbook.Item
	for i := range wsdp.UpdateBids {
		p, err := strconv.ParseFloat(wsdp.UpdateBids[i][0].(string), 64)
		if err != nil {
			return err
		}
		a, err := strconv.ParseFloat(wsdp.UpdateBids[i][1].(string), 64)
		if err != nil {
			return err
		}

		updateBid = append(updateBid, orderbook.Item{Price: p, Amount: a})
	}

	for i := range wsdp.UpdateAsks {
		p, err := strconv.ParseFloat(wsdp.UpdateAsks[i][0].(string), 64)
		if err != nil {
			return err
		}
		a, err := strconv.ParseFloat(wsdp.UpdateAsks[i][1].(string), 64)
		if err != nil {
			return err
		}

		updateAsk = append(updateAsk, orderbook.Item{Price: p, Amount: a})
	}

	return b.Websocket.Orderbook.Update(&wsorderbook.WebsocketOrderbookUpdate{
		Bids:     updateBid,
		Asks:     updateAsk,
		Pair:     currencyPair,
		UpdateID: wsdp.LastUpdateID,
		Asset:    asset.Spot,
	})
}